You’ve probably noticed by now that aluminum foil has two sides: one that’s shiny and one that’s dull. Some folks like to cook on the shiny side, and others prefer the dull side, but who is right? And what does it all mean?

Does the shiny side reflect more heat, resulting in a crispier finish? Or maybe the dull side is a better conductor, creating a more even cooking surface?

It’s a mystery that we’re sure not every home-cook has spent time thinking about, but if you’re one who has you’ve come to the right place. We’re going to break it down for you with help from the experts.

Here’s the important thing you need to know: if you use the shiny side, you’re doing it right. And if you use the dull side, you’re also doing it right. According to Reynold’s Kitchen, the difference between the two sides has nothing to do with cooking. It’s just a result of manufacturing.

The foil is ‘milled’ in layers during production. Milling is a process whereby heat and tension is applied to stretch the foil to the desired thickness. We mill two layers in contact with each other at the same time, because if we didn’t, the foil would break during the milling process. Where the foil is in contact with another layer, that’s the ‘dull’ side. The ‘shiny’ side is the side milled without being in contact with another sheet of metal. The performance of the foil is the same, whichever side you use.

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The shiny side is face-up on the roll, and the dull side is on its underside.

In other words, feel free to use whatever side makes you happy.

But, if you are using non-stick foil, there is a difference between the two sides because the non-stick coating is only applied to one side. If that’s the product you’re using, the dull side is what you want. (It’s been imprinted with “non-stick side” if you should forget.)